Flex joint for downhole drilling applications

Abstract

A technique facilitates drilling applications by providing a unique flex joint. In one embodiment, the flex joint has an adjustable bending stiffness while being much more compact than conventional flex joints. The flex joint also may be designed to de-couple bending moments from the tool joints and, in some applications, can operate as an active vibration and shock control sub by incorporating suitable sensors and a hydraulic actuator system. The design also enables incorporation of other features, such as electrical insulation features disposed above and/or below the flex joint. In some applications, the flex joint also may have an electrical feed through.

What is claimed is: 
     
       1. A method, comprising:
 constructing a flex joint with a first component pivotably coupled to a second component via a universal joint, the bending stiffness between the first component and the second component being adjustable via an adjustable spring assembly; 
 coupling the flex joint into a drill string; 
 adjusting the adjustable spring assembly to provide a desired bending stiffness; 
 sensing relative motion between the flex joint components via a sensor; 
 outputting data from the sensor to a control system employed to monitor action of the flex joint; 
 based on the data, using actuators to adjust operation of the flex joint to reduce undesirable motion; and 
 limiting the degree of bending of the flex joint with a sleeve and an adjustment mechanism mounted to the sleeve. 
 
     
     
       2. The method as recited in  claim 1 , further comprising limiting the degree of bending of the flex joint with a sleeve extending past a universal joint. 
     
     
       3. The method as recited in  claim 1 , further comprising placing an electrical feed through the flex joint. 
     
     
       4. The method as recited in  claim 1 , wherein using comprises using a hydraulic actuator in the flex joint to reduce vibration. 
     
     
       5. The method as recited in  claim 1 , wherein constructing comprises constructing the flex joint with an adjustable bow spring assembly. 
     
     
       6. The method as recited in  claim 5 , further comprising providing electrical insulation of components of the flex joint. 
     
     
       7. The method as recited in  claim 1 , wherein coupling comprises coupling the flex joint into a drill string comprising a bottom hole assembly having a rotary steerable system to steer a drill bit.